Autoxydationsprodukte des Guaiazulens

Zusammenfassung Guaiazulen wird bei Luftzutritt durch Autoxydation verändert. Die dabei auftretenden Produkte wurden chromatographisch aufgetrennt und die drei als Hauptmenge auftretenden Verbindungen charakterisiert: 3.3-Diguaiazulenyl, 1.4-Dimethyl-3-(3-guaiazulenyl)-6-isopropyl-5H-inden-5-on, 1.4-Dimethyl-3-(3-guaiazulenyl)-5-oxo-6-isopropyl-5H-inden-7-aldehyd.

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Autoxidation products of guaiazulene

Guaiazulene exposed to air undergoes autoxidation. The products were separated by chromatography, and the three major products characterized: 3.3-diguaiazulenyl, 1.4-dimethyl-3-(3-guaiazulenyl)-6-isopropyl-5H-inden-5-one, and 1.4-Dimethyl-3-(3-guaiazulenyl)-5-oxo-6-isopropyl-5H-inden-7-aldehyd.

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Herrn Prof. Dr.H. Nowotny gewidmet.     

Potentiometric studies of ternary complex formation Cu(II), Ni, Zn or Cd iminodiacetic acid/amino-acid complexes

The formation constants, log K(mab), for the reactions MA + B right harpoon over left harpoon MAB [where M = Cu(II), Ni, Zn or Cd, A = terdentate ligand and B = bidentate or terdentate ligand] have been determined. Potentiometric evidence is presented for the stepwise addition of the secondary ligand B to the 1:1 metal iminodiacetate (MA). The formation constants and the free energies of formation (DeltaG) have been calculated at 25 +/- 1 degrees and mu = 0.10. The order in terms of secondary ligands has been found to be ASPA > Gly > Aln and Gly > Aln > ASPA with iminodiacetic and nitrilotriacetic acid as primary ligands respectively (ASPA = aspartic acid, Gly = glycine, Aln = dl-alanine). The plot of log K(mab) against log k(mb)(2) shows a linear relationship between the formation constants of the ternary and 1:2 M(II)secondary ligand complexes.     

Force Constants and Bond Orders of Nitrogen Bonds

The force constants and the corresponding bond orders of nitrogen bonds have been calculated from the vibrational spectra (infrared and Raman spectra) of a great number of nitrogen compounds. Plotting the maximum bond order of stable nitrogen bonds against the sum of Pauling's electronegativities of the bonding partners (Σx) leads to one continuous curve for the N? X bonds where X represents elements of the first and the second short period of the periodic table. Furthermore, when the bonds formed between these elements are arranged in a coordinate system in such a way that the position of each bond is determined by the difference between the electronegativities of the bonding partners (Δx along the ordinate) and the sum of the electronegativities of the bonding partners (Σx along the abscissa), the bonding partners capable of forming multiple bonds all lie within a closed domain, where their position can be correlated with their polymerizability and other reactivities of the multiple bonds. Also discussed are the orders of bonds between nitrogen and some transition elements. In an appendix, the present methods used to calculate force constants and bond orders are surveyed.     

Ab initio MO-SCF calculation on a model of anomalous water

Ab initio calculations are carried out on the planar hexamer model of anomalous water using a variety of basis sets. The results are compared to results of similar calculations on free water and water in the ice I-like puckered ring configurations.

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Zusammenfassung Es werden ab initio-Rechnungen für das planare Hexamer-Modell von anomalem Wasser unter Verwendung mehrerer BasissÄtze durchgeführt. Die Ergebnisse werden mit Resultaten Ähnlicher Rechnungen über freies Wasser und Wasser in der I-Eis Ähnlichen Konfiguration verzerrter Ringe verglichen.

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Résumé Calculs ab initio sur le modèle hexamérique plan de l'eau anormale en utilisant différentes bases. Les résultats sont comparés à ceux de calculs similaires sur l'eau libre et sur l'eau dans une configuration cyclique compacte analogue à celle de la glace I.

     

Neutronenaktivierungsanalytische Bestimmung von Osmium in Geologischen Proben

A neutron activation analysis procedure was developed for the determination of osmium in geological materials. The method consists in the measurement of the 129.4 keV γ-rays of¹⁹¹Os after radiochemical separation of osmium. The sample decomposition, the chemical separation process and the optimal measuring conditions are described and discussed.      

Rearrangements of organometallic compounds : XVII. Synthesis of lactones via the titanium-catalyzed hydromagnesiation of alkenols

An efficient, two-step synthesis is presented for preparing γ- and δ-lactones from aldehydes or ketones. (1) the addition of vinyl- or allyl-Grignard reagents to the appropriate carbonyl substrate; and (2) the titanium-catalyzed hydromagnesiation of the resulting alkenols with ethyl Grignard reagent and (η⁵-C₅H₅)₂TiCl₂, followed by carbonation. The selectivity of hydrometallation observed with 3-butenyl(methyl)vinylcarbinol indicates the importance of alkoxytitanium hydrides in determining the course of reaction.     

Simultaneous observation of coherent and incoherent resonant re-emission in the condensed phase

We report simultaneous observation of coherent resonance Raman scattering and incoherently broadened resonance fluorescence following excitation of cytochrome c in the α(0, 0) region. The influence of incoherent broadening processes on resonance Raman scattering experiments is considered.     

Analysis of DTA curves and calculation of kinetic data using computer technique

Principles of two computer programs useful for the evaluation of heterogeneous kinetics are described.The first program ALANTA allows to obtain the non-isothermal kinetic curve from the shape of general DTA peak using the DTA-equation derived elsewhere¹.The second program SQUEST determines the kinetic mechanism which is the most appropriate to a given non-isothermal kinetic curve and evaluates the corresponding kinetic parameters. The program decides between 19 kinetic models and uses both integral and differential methods of evaluation.     

Distribution of polymer deposition in plasma polymerization. III. Effect of discharge power

Distribution of polymer deposition in an inductively coupled rf discharge system is studied as a function of level of discharge power with acetylene and styrene as monomers. When a fixed flow rate is used, the discharge power has a relatively small effect on the pattern of distribution of polymer deposition as long as values of W/FM, where W is discharge wattage, F is flow rate, and M is molecular weight of monomer, are maintained above a critical level to maintain full glow in the reaction tube. It has been shown that plasma polymerization of two monomers which have different molecular weights can be compared in a fair manner by selecting conditions to yield similar value of W/FM.     

Ta4P4S29: A new tunnel structure with inserted polymeric sulfur

Ta₄P₄S₂₉ was prepared from the elements heated together in stoichiometric proportions in an evacuated Pyrex tube for 10 days at 500°C. The crystal symmetry is tetragonal, space group P4₃2₁2, with the cell parameters: a = b = 15.5711(7) Å, c = 13.6516(8) Å, V = 3309.9(5) ų, and Z = 4. The structure calculations were conducted from 2335 reflections and 146 variables, leading to R = 0.033. The structure basic framework, corresponding to the chemical composition [TaPS₆], is made of biprismatic bicapped [Ta₂S₁₂] units (average d_TaS = 2.539 Å), including sulfur pairs (average d_SS = 2.039 Å), bonded to each other through [PS₄] tetrahedral groups (average d_PS = 2.044 Å) sharing sulfurs. This framework leaves large tunnels running along the c axis of the cell and in which (S₁₀)_∞ sulfur chains are found to be inserted (average d_SS = 2.052 Å and SSS = 105.75°). Diamagnetic and semiconducting Ta₄P₄S₂₉ can be formulated: Ta^V₄P^V₄(S^?II)₁₆(S^?II₂)₄(S⁰₅).